?? dac.asm
字號:
TBLR NEXTVALUE ;Read the next value from the table and store into NEXTVALUE
LACC NEXTVALUE ;Load the ACC with NEXTVALUE
SUB VALUE ;Subtract the previous value
SACL DIFFERENCE ;Store the difference between the values into DIFFERENCE
LT DIFFERENCE ;Load the TREG with DIFFERENCE
MPY REMAINDER ;Multiply the DIFFERENCE with REMAINDER
PAC ;Move the product to the ACC
SACH REMAINDER,1 ;Store the upper byte to REMAINER and shift left by 1, Q15
LACC REMAINDER ;Load ACC with new REMAINDER
ADD VALUE ;Add VALUE to get the new interpolated value
SACL VALUE ;Store the interpolated value into VALUE
LT VALUE ;Load the TREG with the new interpolated VALUE
MPY MAG1 ;Multiply VALUE by a magnitude
PAC ;Move the product to ACC
SACH DAC1VAL,1 ;Store the new value to DAC0VAL to output, shift to get Q15
;The following section performs the necessary calculations for the third sine wave
LACC MODREG2 ;ACC loaded with the counting register
ADD FREQSTEP2 ;Counting Register increased by specific step
SACL MODREG2 ;Store the updated the counter value
LACC MODREG2,8 ;Reload the new counter value but shift left by 8 bits
SACH TABLE ;Store the high bit into the TABLE as pointer to lookup table
SFR ;Shift the value to the right convert to Q15
AND #07FFFh ;Make sure the Q15 value is positive
SACL REMAINDER ;Store the fractional value of the counting register
LACC TABLE ;Load the accumulator with the proper index value
ADD TOPTABLE ;Displace the ACC with the starting address
TBLR VALUE ;Read the value from the table and store into VALUE
ADD #1 ;Increment the ACC to the next address
TBLR NEXTVALUE ;Read the next value from the table and store into NEXTVALUE
LACC NEXTVALUE ;Load the ACC with NEXTVALUE
SUB VALUE ;Subtract the previous value
SACL DIFFERENCE ;Store the difference between the values into DIFFERENCE
LT DIFFERENCE ;Load the TREG with DIFFERENCE
MPY REMAINDER ;Multiply the DIFFERENCE with REMAINDER
PAC ;Move the product to the ACC
SACH REMAINDER,1 ;Store the upper byte to REMAINER and shift left by 1, Q15
LACC REMAINDER ;Load ACC with new REMAINDER
ADD VALUE ;Add VALUE to get the new interpolated value
SACL VALUE ;Store the interpolated value into VALUE
LT VALUE ;Load the TREG with the new interpolated VALUE
MPY MAG2 ;Multiply VALUE by a magnitude
PAC ;Move the product to ACC
SACH DAC2VAL,1 ;Store the new value to DAC0VAL to output, shift to get Q15
;The following section performs the necessary calculations for the fourth sine wave
LACC MODREG3 ;ACC loaded with the counting register
ADD FREQSTEP3 ;Counting Register increased by specific step
SACL MODREG3 ;Store the updated the counter value
LACC MODREG3,8 ;Reload the new counter value but shift left by 8 bits
SACH TABLE ;Store the high bit into the TABLE as pointer to lookup table
SFR ;Shift the value to the right convert to Q15
AND #07FFFh ;Make sure the Q15 value is positive
SACL REMAINDER ;Store the fractional value of the counting register
LACC TABLE ;Load the accumulator with the proper index value
ADD TOPTABLE ;Displace the ACC with the starting address
TBLR VALUE ;Read the value from the table and store into VALUE
ADD #1 ;Increment the ACC to the next address
TBLR NEXTVALUE ;Read the next value from the table and store into NEXTVALUE
LACC NEXTVALUE ;Load the ACC with NEXTVALUE
SUB VALUE ;Subtract the previous value
SACL DIFFERENCE ;Store the difference between the values into DIFFERENCE
LT DIFFERENCE ;Load the TREG with DIFFERENCE
MPY REMAINDER ;Multiply the DIFFERENCE with REMAINDER
PAC ;Move the product to the ACC
SACH REMAINDER,1 ;Store the upper byte to REMAINER and shift left by 1, Q15
LACC REMAINDER ;Load ACC with new REMAINDER
ADD VALUE ;Add VALUE to get the new interpolated value
SACL VALUE ;Store the interpolated value into VALUE
LT VALUE ;Load the TREG with the new interpolated VALUE
MPY MAG3 ;Multiply VALUE by a magnitude
PAC ;Move the product to ACC
SACH DAC3VAL,1 ;Store the new value to DAC0VAL to output, shift to get Q15
;Sets the values to 12 bits
LDP #0 ;This section outputs the SINE wave to the DAC
LACC DAC0VAL ;ACC = DAC0VAL - entry from the lookup table
ADD #8000h ;Displace the value half the maximum
SFR ;Shift over 4 places since the DAC is 12bits
SFR
SFR
SFR
SACL DAC0VAL ;Store the new 12 bit value into DAC0VAL
LACC DAC1VAL ;ACC = DAC0VAL - entry from the lookup table
ADD #8000h ;Displace the value half the maximum
SFR ;Shift over 4 places since the DAC is 12bits
SFR
SFR
SFR
SACL DAC1VAL ;Store the new 12 bit value into DAC1VAL
LACC DAC2VAL ;ACC = DAC0VAL - entry from the lookup table
ADD #8000h ;Displace the value half the maximum
SFR ;Shift over 4 places since the DAC is 12bits
SFR
SFR
SFR
SACL DAC2VAL ;Store the new 12 bit value into DAC2VAL
LACC DAC3VAL ;ACC = DAC0VAL - entry from the lookup table
ADD #8000h ;Displace the value half the maximum
SFR ;Shift over 4 places since the DAC is 12bits
SFR
SFR
SFR
SACL DAC3VAL ;Store the new 12 bit value into DAC3VAL
OUT DAC0VAL,DAC0 ;Stores the 12 bit value into DAC0 register
OUT DAC1VAL,DAC1 ;Stores the 12 bit value into DAC1 register
OUT DAC2VAL,DAC2 ;Stores the 12 bit value into DAC2 register
OUT DAC3VAL,DAC3 ;Stores the 12 bit value into DAC3 register
OUT DAC0VAL,DAC_UPDATE ;Causes the DAC to output the value
B SINE
;-------------------------------------------------------
; Sine look-up table
; No. Entries : 256
; Angle Range : 360 deg
; Number format : Q15 with range -1 < N < +1
;-------------------------------------------------------
;SINVAL ; Index Angle Sin(Angle)
STABLE .word 0 ; 0 0 0.0000
.word 804 ; 1 1.41 0.0245
.word 1608 ; 2 2.81 0.0491
.word 2410 ; 3 4.22 0.0736
.word 3212 ; 4 5.63 0.0980
.word 4011 ; 5 7.03 0.1224
.word 4808 ; 6 8.44 0.1467
.word 5602 ; 7 9.84 0.1710
.word 6393 ; 8 11.25 0.1951
.word 7179 ; 9 12.66 0.2191
.word 7962 ; 10 14.06 0.2430
.word 8739 ; 11 15.47 0.2667
.word 9512 ; 12 16.88 0.2903
.word 10278 ; 13 18.28 0.3137
.word 11039 ; 14 19.69 0.3369
.word 11793 ; 15 21.09 0.3599
.word 12539 ; 16 22.50 0.3827
.word 13279 ; 17 23.91 0.4052
.word 14010 ; 18 25.31 0.4276
.word 14732 ; 19 26.72 0.4496
.word 15446 ; 20 28.13 0.4714
.word 16151 ; 21 29.53 0.4929
.word 16846 ; 22 30.94 0.5141
.word 17530 ; 23 32.34 0.5350
.word 18204 ; 24 33.75 0.5556
.word 18868 ; 25 35.16 0.5758
.word 19519 ; 26 36.56 0.5957
.word 20159 ; 27 37.97 0.6152
.word 20787 ; 28 39.38 0.6344
.word 21403 ; 29 40.78 0.6532
.word 22005 ; 30 42.19 0.6716
.word 22594 ; 31 43.59 0.6895
.word 23170 ; 32 45.00 0.7071
.word 23731 ; 33 46.41 0.7242
.word 24279 ; 34 47.81 0.7410
.word 24811 ; 35 49.22 0.7572
.word 25329 ; 36 50.63 0.7730
.word 25832 ; 37 52.03 0.7883
.word 26319 ; 38 53.44 0.8032
.word 26790 ; 39 54.84 0.8176
.word 27245 ; 40 56.25 0.8315
.word 27683 ; 41 57.66 0.8449
.word 28105 ; 42 59.06 0.8577
.word 28510 ; 43 60.47 0.8701
.word 28898 ; 44 61.88 0.8819
.word 29268 ; 45 63.28 0.8932
.word 29621 ; 46 64.69 0.9040
.word 29956 ; 47 66.09 0.9142
.word 30273 ; 48 67.50 0.9239
.word 30571 ; 49 68.91 0.9330
.word 30852 ; 50 70.31 0.9415
.word 31113 ; 51 71.72 0.9495
.word 31356 ; 52 73.13 0.9569
.word 31580 ; 53 74.53 0.9638
.word 31785 ; 54 75.94 0.9700
.word 31971 ; 55 77.34 0.9757
.word 32137 ; 56 78.75 0.9808
.word 32285 ; 57 80.16 0.9853
.word 32412 ; 58 81.56 0.9892
.word 32521 ; 59 82.97 0.9925
.word 32609 ; 60 84.38 0.9952
.word 32678 ; 61 85.78 0.9973
.word 32728 ; 62 87.19 0.9988
.word 32757 ; 63 88.59 0.9997
.word 32767 ; 64 90.00 1.0000
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